mlton/backend/scale.fun

   1 (* Copyright (C) 2004-2007 Henry Cejtin, Matthew Fluet, Suresh
   2  *    Jagannathan, and Stephen Weeks.
   3  *
   4  * MLton is released under a BSD-style license.
   5  * See the file MLton-LICENSE for details.
   6  *)
   7
   8 functor Scale (S: SCALE_STRUCTS): SCALE =
   9 struct
  10
  11 open S
  12
  13 datatype t = One | Two | Four | Eight
  14
  15 val toString =
  16    fn One => "1"
  17     | Two => "2"
  18     | Four => "4"
  19     | Eight => "8"
  20
  21 val layout = Layout.str o toString
  22
  23 val fromInt: int -> t option =
  24    fn 1 => SOME One
  25     | 2 => SOME Two
  26     | 4 => SOME Four
  27     | 8 => SOME Eight
  28     | _ => NONE
  29
  30 val fromBytes: Bytes.t -> t option =
  31    fromInt o Bytes.toInt
  32
  33 val toInt: t -> int =
  34    fn One => 1
  35     | Two => 2
  36     | Four => 4
  37     | Eight => 8
  38
  39 end